BACKGROUND The purpose of this study was to compare the effectiveness of debris removal between EndoVac, PiezoFlow, or needle irrigation (Max-i-Probe) in mandibular molars. METHODS The mesial roots of 30 extracted mandibular molars were mounted in resin by using the K-Kube and then sectioned at 2 and 4 mm from the apex. The specimens were reassembled and instrumented to size 40/0.04. A standard irrigation protocol was used during instrumentation in the PiezoFlow and Max-i-Probe groups. During instrumentation of teeth in the EndoVac group, the manufacturer's recommendations for irrigation were followed. Images of the canals and isthmuses were taken before final irrigation. The percentage of cleanliness for each canal and isthmus was calculated by using interactive software. The specimens were reassembled for final irrigation with EndoVac, PiezoFlow, and Max-i-Probe by using similar volumes of irrigants. Images were again used to calculate cleanliness. Comparisons of canal and isthmus cleanliness before and after final irrigation were made by using paired t tests, and the groups were compared with repeated-measures analysis of variance (P < .05). RESULTS There were no statistically significant differences in canal and isthmus cleanliness among all 3 groups at 2 and 4 mm from working length before or after final irrigation. Canal and isthmus cleanliness significantly improved at all levels after the final irrigation regimen in each group. CONCLUSIONS Final irrigation by using EndoVac, the PiezoFlow, or Max-i-Probe with similar volumes of irrigants significantly improved canal and isthmus cleanliness.